Fluid fossil fuels such as oil and natural gas are becoming scarce as a result of the increased world population and the increased uses for such fuels. Furthermore, since there is reason to believe that the steady importation of fluid fossil fuels into the United States could be disrupted from time to time, there is a need for a method for converting coal into liquid and gaseous fuels.
Heretofore, pyrolysis processes employing particulate solid heating media and transport reactors have had a serious problem maintaining a steady and uniform flow of particulate solid heating media into the reactor zone. Upsets and disturbances to the flow of heating media frequently occur in such systems which result in a drop in yield of pyrolysis vaporous product and, in some cases, the formation of plugs in the transport reactor or elsewhere in the system. In addition, such upsets usually result in inefficient separation of the char product from the condensable vaporous product. This in turn results in ultimate contamination of the liquid product with char product. To remove such char from the liquid product requires expensive and time-consuming separation steps which become very costly and can cause the process to be uneconomical.
The present invention is an improvement in the state of art of pyrolysis because it reduces the tendency for such upsets and disturbances to cause non-uniform and non-continuous flow of particulate solid heating media into the pyrolysis zone. The present invention, therefore, has as an objective--that of providing a substantially uniform and continuous flow of particulate solid heating media into the pyrolysis zone when upstream upsets and disturbances in the flow of particulate solid heating media occur. The present invention also has as objectives improving the yield of recoverable liquid product, reducing the formation of plugs in the reactor and downstream equipment therefrom, and reducing or eliminating the need for separation of char product from liquid product.